1. Field of the Invention
The present invention relates to an improved pressure/vacuum relief valve apparatus and more particularly relates to a valve apparatus which can relieve a vessel to which it is affixed of either pressure or vacuum therewithin. Even more particularly the present invention relates to an improved adjustable relief valve apparatus (pressure or vacuum relief) that can be cleaned in place using remote instrumentation.
2. General Background
In the industry of beverage, bio-engineering, pharmaceutical, cosmetics and food processing, control of bacteria is one of the most important features of any equipment used. The equipment must function to the maximum design capabilities and also be easily cleaned to eliminate and prevent the accumulation and build-up of food, dried liquid or the like that can function as a medium for growth of harmful bacteria and other such microorganisms.
In the processing of some food and beverage products (e.g. beer), pressure is produced as a by-product of the process. Containing and controlling gaseous by-products is very important to producing the quality and maintaining the desirable characteristics of the final product. For example, in the fermentation process of beer, carbon dioxide is produced and must be contained for further use in the aging process of the beer.
A very important piece of equipment used in food/beverage processing is an over-pressure relief device known as a safety relief valve. Certain conditions can also exist that result in a vacuum being present in the system. In these applications a combination pressure and vacuum relief valve is used to satisfy both conditions. The problem that exists with such valve devices in use today for over-pressure and vacuum relief, is that these prior art devices do not clean themselves i.e., permit in-place cleaning or sterilization, or remote operations. The food uses sugar and other ingredients in the processing to the final product. During some food processing ingredients can collect in crevices and corners As aforementioned, these ingredients can solidify and become a breeding place for harmful bacteria. However, the solidification of ingredients can create another significant problem that can render the over-pressure/vacuum relief equipment inoperable when the liquids solidify, adhering the working parts together. This potentially creates a very dangerous and unreliable condition that may result in a damage or loss of very expensive equipment and product. Even worse is the possible injury or loss of life for personnel working in the area of such vessels.
Several patents have been granted for valves which operate to relieve pressure and/or vacuum. Even some of these valves relieve both pressure and vacuum in the same apparatus. Examples of relief valve can be seen in the following patents.
__________________________________________________________________________ U.S. Pat. No. TITLE INVENTOR __________________________________________________________________________ 4,091,837 FREEZERPROOF BREATHER VALVE EDMUNDS 4,016,903 PILOT OPERATED PRESSURE AKASHI AND VACUUM RELIEF VALVE 3,100,503 PILOT OPERATED PRESSURE TENNIS AND VACUUM RELIEF VALVE 4,323,096 COMBINATION VACUUM RELIEF DUGGE VALVE AND PRESSURE RELIEF VALVE WHICH ARE PROTECTED FROM THE ATMOSPHERE 2,989,072 RELIEF VALVE FOR HIGH PRESSURES BANKER 3,441,050 PRESSURE EQUALIZING VALVE SANCHEZ 1,990,371 COMBINED VACUUM AND RELIEF VALVE CHADWICK 725,782 DOUBLE ACTING VALVE FOR BEER VATS SCHMAHL & ZIMMERMAN __________________________________________________________________________
An early patent showing a double acting valve for a beer vat is shown in U.S. Pat. No. 725,782 entitled "Double Acting Valve For Beer Vats". In column 1, line 16 and following, the '782 patent discusses the problem of allowing air to be drawn into the vat when beer is drawn from the lower end thereof and in order to vent gas pressure discharged through the valve when that pressure exceeds a certain value.
The Chadwick U.S. Pat. No. 1,990,371 discloses another early version of a combined vacuum and relief valve apparatus. Other examples of early pressure equalizing valves can be seen in the Banker U.S. Pat. Nos. 2,989,072 and in the Sanchez 3,441,050.
The concept of using a pilot to operate pressure and relief valves can be seen in the U.S. Pat. Nos. 3,100,503 to Tennis and 4,016,903 to Akashi also discloses the concept of double acting relief valves.
The Crosby valve division of Moorco of Wrenthamas, Massachusetts manufactures a pressure vacuum relief valve known by its designation "Crosby PVR". The valve includes a body having a pressure relief disc and a vacuum disc. Springs are provided for biasing the pressure relief disc and the vacuum disc with certain load values.